Five Macaca nemestrina that were infected with HIV-2287 and treated with d4T (Stavudine) remain in good health 2.5 years after drug therapy was discontinued, despite persistent virus infection. In vitro tests have suggested that the CD8+ cell population has a role in maintaining the low levels of circulating virus and the normal levels of CD4+ cells in the peripheral blood. Additional in vitro tests are currently underway, as the necessary preliminary step to the initiation of the in vivo experiment. Then we will attempt to reduce the number circulating CD8+ cells in vivo and monitor the effect produced on the levels of circulating virus and CD4+ cells.